Hi, Robert!
I'm on the way out the door for my normal
airline trip but happen to be on as I found
a message for "justbrits" (he's mad at me,
as if you couldn't guess!) which should
help him understand he made a mistake.
Anyway, Vizard does mention bore flex
in his book and I think It comes under
"Big Motors"; don't have this handy right
now.
I'll have to do this from memory, so I could be a little wrong on this.
Beyond a certain bore (73.5mm+, I think,
though it may be more), the cylinder walls
get thin enough to really weaken, especially on thin flange blocks
(1275's)
so that at high rpm, the block or walls
will actually "flex", causing loss of compression and oil control (rings
no
longer making proper contact with
"moving" cylinder walls), along with
attendant blow-by pressurizing the
crankcase, of course.
The A+ blocks are supposed to be a lot
stronger in this respect, over and above
the thick flange pre-A+ 1275's.
I wish I had the time to find the right page
but I gotta split.
Hope this helps!
Cap'n. Bob
'61 :{)
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